As warm, moist air over water rises it releases its water into the atmosphere, creating clouds that can trap a lot of energy. This can lead to storms, especially if the wind speeds are fast enough.
When the wind speeds are faster than 39 miles per hour (63 kph) they become tropical storms and when they’re faster than 74 miles per hour (119 kph) they’re called hurricanes. But only a small number of storms actually grow into hurricanes, and even fewer hurricanes turn into stronger hurricanes.
The first thing that’s needed for a storm to form is warm ocean water and moist, hot air above it. Usually, this means that the ocean is at least 80 degrees F.
After the storm has formed and gathered enough energy, it starts to circulate around a center of low pressure called an eyewall. This process is controlled by the Coriolis effect, which is caused by the rotation of the Earth.
This force causes air to curve counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. This is the main reason why hurricanes cannot form within 300 miles of the equator or at lower latitudes.
When a hurricane gets closer to the North American continent it often curves northward and may even come close to making landfall in the United States. This is due to the influence of high and low-pressure systems that surround a tropical storm’s track, such as a Bermuda High or a subtropical ridge.
